General remarks on maximum attainable yield

A large positive value of AO at 25 C implies a small value of Kp at this temperature, in accordance with 

This does not necessarily mean that the reaction in question is unsuitable for preparative or manufacturing purposes. In the first place, it may occur that the equilibrium becomes more favourable at some other temperature in endothermic reactions, for example, the equilibrium is favoured by a rise of temperature, as follows fiiom the 

Let X be the number of moles of C which are obtained at equilibrium from a reactant mixture containing originally one mole of A and two moles of B. The equilibrium gas therefore consists of (l—rc) moles of A, (2—2x) moles of.B and a moles ofC and the equilibrium relation can be expressed as 

It may be remarked that incomplete reaction does not necessarily imply wastage of the unused reactants. Ammonia synthesis is usually 

The converse situation to that which has been discussed above is where there is an increase in the number of molecules. Gas reactions of this type are favoured by a decrease of pressure, or alternatively by dilution with an inert gas. Under practical conditions the advantages of such a procedure might be seriously offset by decreased rate of reaction. 

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